Read the full text of Cymbeline Act 2 Scene 2 with a side-by-side translation HERE.
Back in her room, Imogen goes to bed. She prays that the fairies and tempters of the night will not harm her, and then she goes to sleep.
The trunk Imogen promised to guard is safely stowed away in her room.
Just then, Iachimo emerges from the trunk. What? Is this for real?
It totally is: Iachimo couldn't get Imogen to agree to cheat on Posthumus, so he'll just have to trick Posthumus into believing she did.
Iachimo looks for proof that he was with Imogen. He takes in every detail about the room. But then he figures that he should come back with more convincing proof than just an inventory of her curtains and bed.
Aha: the bracelet. Iachimo takes the bracelet off Imogen's wrist, and then he sees a mole "clinque-spotted" (translation: it's got five spots) on her breast.
Iachimo's got the evidence he needs to convince Posthumus, so he runs off before he's discovered.